1. Field of the Invention
This invention relates to polyurethanes. More particularly, it relates to polyurethanes, having improved physical properties, derived from a polymer polyol, and to a process for producing the same.
2. Description of the Prior Art
It is well known that polyurethane foams and elastomers having load-bearing properties can be obtained from polymer polyols, which are prepared by polymerization of one or more ethylenically unsaturated monomers (such as acrylonitrile and combination thereof with styrene) in situ in polyols and have polymer content of 20-30% by weight. A few documents disclose pendant hydroxyl-containing polymer polyols, but polyurethanes prepared therefrom have physical properties not so good as those produced from polymer polyol of acrylonitrile alone.